In article <49tt44$otg at eis.wfunet.wfu.edu> laubach at biogfx.bgsm.wfu.edu (Mark
Laubach) writes:
My own search of the literature indicates that there is no evidence for
precise timing of spikes as a neural code in awake, behaving subjects.
Besides Abeles, whom you mention below, there is also recent work from
Singer's lab in Frankfurt using behaving animals.
Rather, those who have searched for such coding have instead found that
local changes in firing rate, not the precise temporal pattern of spikes,
may serve as a code for environmental stimuli, movements, task
contingiencies, etc. (e.g., Richmond's work on visual cortex).
I always attribute such results to overtraining: if your animal has spent half
a year to a year on learning a very specialised, narrowly defined task, it
will develop a specialised (group of) cell(s) subserving that task, and the
flexible mechanism for temporal binding is no longer required. See von der
Malsburg's recent article in Current Opinion in Neurobiology.
I know that some (e.g., Abeles) have reported that precise spike patterns
across small ensembles of neurons can occur in behaving subjects, but have
these patterns been shown to "be good for anything" with regard to the
subject's performance of the task?
Firstly - what more can you, realistically, want from an experiment using whole
brains? Secondly - these temporal relationships are highly reproducible to the
millisecond level (while some dispute that nerve cells are even able to do
this, e.g. Newsome et al. ...); Occam's razor tells you that evolution didn't
implement this by accident.
Jan